1) Field of the Invention
The present invention relates to a method and apparatus for adhesive bonding of a plurality of peel-and-stick or self-stick porous products to a common carrier (e.g., release sheet or paper) of indeterminate length, for automatic dispensing of the self-stick, porous products from the common carrier, and for refurbishing the common carrier for reuse.
2) Description of Related Art
Fiberglass panels coated with an adhesive which can be reactivated are used for a variety of applications. For instance, insulation panels of fiberglass batting for heating, ventilating and air conditioning (HVAC) units are known to be bonded to metal housings by a spray application of a hot melt adhesive composition. The adhesive is sprayed onto either the metal housing or the fiberglass insulation, as disclosed in U.S. Pat. No. 5,106,447 of Di Rado et al. The fiberglass insulation is to protect against weather, reduce sound, stop water vapor from forming on the metal, and separate hot compression units from cold freon gas coils.
Continuous batts of semi-rigid porous materials, such as a foam, cellulose, and/or fibrous materials coated with thermoplastic adhesive which can be reactivated, are known to be for use in automotive trim panels which can be made by using an adhesive coated panel and a shell or substrate and laminating a decorative cover on the adhesive coated side of the panel. These adhesive coated panels can also be used for the manufacture of other automotive products such as floor pads, hood liners, trunk liners, seating, and door panels, such as disclosed in U.S. Pat. No. 5,472,541 to Simmons et al. In the process disclosed in the Simmons et al patent, a powder thermoplastic adhesive is placed on a release coating on a conveyor and heated to a plasticized state. Porous material is then added and the adhesive is reheated to a melted state such that the adhesive bridges, rather than penetrates, the pores of the porous material.
In addition to conventional spray methods, materials can be coated with adhesive by heating the adhesive to a sinter temperature and then transferring the heated adhesive onto the surface of a printing roll. As the flexible material passes between the printing roll and a contact pressure roll, the adhesive is released onto the surface of the material that is in contact with the printing roll. Alternatively, powdered adhesive is sprinkled onto the material and heated with a radiant heat source to a temperature sufficient to melt the adhesive and allow the same to adhere to the underlying material.
These processes are inadequate for a number of reasons. For instance, prior processes apply adhesive to an entire surface of a fibrous material of uniform width. The adhesive adheres only to the surface fiber and surface dust, resulting in a weak interfacial bond between the fibrous material product, e.g. fiberglass product, and the adhesive.
Further, the fibrous material is generally cut to shape after the adhesive is applied. This means that the cutting of uniquely shaped products requires the cutting mechanism to cut through adhesive, which can lead to clogging of the cutting machine, etc. This also leads to substantial waste of the fibrous material and adhesive located outside the boundaries of the desired shape. Also, the common carrier becomes scrap after the product is removed. This waste material has to be disposed of by the customer, such as an HVAC manufacturer, which is costly and environmentally unsound. Furthermore, much if not all of this material could be easily recycled if not for the presence of the adhesive and the burden of shipping the material back to the fibrous material fabricating facility.
Additionally, prior self-stick fiberglass materials conventionally need to be cut to shape by the customer, which is labor intensive and messy.
The conventional processes of applying adhesive to porous mats typically do not include the ability to exclude areas of the mats from application of the adhesive. Such non-adhesive coated areas are sometimes desired for flanges that are not intended to be adhered to a surface and edge portions which otherwise would include exposed glue edges to which dirt and debris collects. Spraying adhesives usually involves airborne solvents or other secondary products which are not environmentally desirable.
Another system uses a vacuum and ramp conveyors designed to compress and draw hot melt adhesive into fiberglass products to increase the bonding strength, as disclosed in EP 0,725,117, published Aug. 7, 1996. While this vacuum system is advantageous over other systems, the use of adhesive drawing vacuums is not applicable to fiberglass materials having a non-porous facing material (e.g., foil or kraft paper) located on the opposite surface of the fiberglass relative to the surface on which the adhesive is applied, because of the inability to produce a vacuum through the nonporous facing material.